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The modern motion picture brings
you. Education. Entertainment.

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That brings the world to the
smallest town the poorest.

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In the street. Which bring
these marvels to you.

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Artists and technicians.

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Put together the mixture of
science which makes actors

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and sets and lights camera

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and cameras there is a roll
of Motion Picture negatives.

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In this camera.

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The finished picture will be on
another roll known as positive film.

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These delicate strips of with their light
sensitive coating on the materials which

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records and transmit the creations
of Hollywood to the world.

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This picture is the story of these films

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and of how the alchemy in Hollywood
makes entertainment out of solar these

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buildings are some of the movie photo
finishers of Motion Picture laboratories in

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Hollywood where you have taken a snapshot
of Junior with your own camera you take

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your roll of film to the photo finish your
next day. So you're finished pictures.

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This is just what happens to movie film
from a studio camera the photographic

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process

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and how it brings a picture to you is
explained by this diagram originated by Dr

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meis when you look at
an object in real life.

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The brain at number one receives an image
of it through the eye in photography the

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object is a large black text two is image
by a lens on a light sensitive film

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and three. The exposure period
produces a latent image on the film

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and four after developing in fixing. A
visible negative image is formed at five.

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It is called a negative image because it
is right where the original object is

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black and vice versa.

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In order to obtain an
image in which the light

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and dark areas are in the correct relationship
this process must be repeated the

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negative is therefore
photographed or printed.

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Light shines through the negative

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and falls upon another light
sensitive film at six

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and produces a latent image it's
seven once more of the developing

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and fixing of the film we veil a permanent
image at eight which is this time a

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positive image of the original object.

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Therefore

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when this positive image at nine is alumina
eight in the brain a ten again sees an

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image which is a faithful reproduction of
that obtained from the original subject.

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What happens to the film chemically
may be expressed in three equation.

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First a latent images form a second.

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It is developed and
finally made permanent.

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The photographic emotion is
made up of millions of tiny.

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Crystals of silver bromide suspended in a
thin layer of Delton This picture shows

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how the crystals actually look when
magnified several thousand times.

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We want to talk about them for a few
minutes in rather technical language.

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Because on their peculiar properties is
based the whole art photography you will

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note that the triangle is a typical shape
in this group. And for simplicity.

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We shall talk about a
single triangular Crystal.

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This crystal is made up
of a pattern of silver

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and Roman irons the silver denoted by a G.

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Very positive charge

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and the Brahman denoted by B R A negative
the significant detail about this crystal

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which makes it a photographic value is a
tiny speck best known as the sensitivity

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spec consisting primarily of silver sulfide
these specks probably formed during the

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manufacture of the emotion.
Let us follow the action.

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When light waves from your favorite movie
star pass into the camera to the emotion.

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If you light quanta strike
this particular Crystal.

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And when a quantum of proper energy
hits a Roman ion it releases

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and electron from the Roman leaving it no
longer an eye on what an atom with zero

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charge the electron is then free to
travel within the crystal just as if the

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crystal were in the electric conductor.

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Indeed we speak of this property of silver
bromide crystals as photo conductance

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since they conduct electricity
when light falls on them.

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Electrons within the crystal travel freely

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and naturally in their wanderings they
find the sensitivity spec since the

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molecular pattern of the spec is such

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that it can trap the electrons like a
positive pole in the crystal the electrons

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released by the action of the light find
themselves clustered about the sensitivity

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spec cumulation of these electrons converts
the spec to a negative pole capable of

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attracting positively charged particles.

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There is at all times within the crystal
a movement of ions through the thermal

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agitation.

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Under ordinary conditions the silver

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and Roman irons moved sluggishly about
occupying vacant places within the crystal

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lattice in this particular Crystal However
something has happened to disturb the

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normal state after being struck by the
light a negative pole was formed at the

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sensitivity spec and now positively charged
silver ions are attracted to the speck.

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We follow the silver ions in their slow
path toward the speck since their movement

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is due to thermal agitation of the
molecules this action is faster

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when the crystal is warm than

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when it is cold which explains why film
is less sensitive in cold weather the

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silver ions progressively
drawn to the spec

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and as fast as they come within its range.

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They are neutralized by the electrons
clustered about the speck.

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Eventually one atom of silver is neutralized
respect for each quantum of light

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which if the crystal

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and the sensitivity spect finds itself
surrounded by a group of silver atoms.

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It is the aggregate of these clusters of
silver present in the crystals which were

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struck by light which are the latent image
in the film this image is called latent

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because it is quite invisible and of
no use to us until a developer reveals

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that the latent images permanent this
crystal pattern being stable at ordinary

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temperatures and fact.

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Film exposed by the Andre expedition

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and abandoned in the Arctic
was found thirty years later

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and developed to give
satisfactory pictures.

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Following the neutralization of the
electrons at the spec by the silver ions

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suspect regains its original
ability to trap electrons

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and on immersion in a developer

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and ionized molecule hydroquinone bearing
a negative charge is attracted to the

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specter or latent image. The secret
of the use of certain weight.

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Cing agents as developers is

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that they're like trick potential is of
just the right order to be attracted to the

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specs.

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But they are not powerful enough to reduce
the silver ions in neighboring crystals

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which have not been exposed to light.

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One molecule of Heidrick
unknown appears at the spec

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and loses its negative charge which
is an electron to the group.

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Thus negatively charged the spec is once
more the target for wandering silver ions

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and as fast as one silver ion arrives
at the Spectrum look at lies itself

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and leaves the group
again positively charged

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and not a molecule of
hiding going on appears

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and deposits another electron if this
keeps up long enough all the silver ions

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within one crystal are
reduced to metallic silver

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and we have a black deposit
forming part of a visible image.

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The bromide ions move out of the crystal
and are released in the developer.

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To show how a picture of light

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and dark tones may result from a
collection of silver particles.

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Let us see what happens when crystals are
given exposures of different intensity.

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This crystal receiving much light
has many electrons released

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and many silver atoms formed
following development.

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It is completely reduced
to metallics over.

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The next Crystal receiving a moderate
amount of light has fewer ions reduced to

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atoms and has some of the silver and
Brahman ions left in their places.

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The third Crystal receiving little
light has few electrons released.

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And a few silver atoms formed.

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I want three crystals of
them have this appearance.

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It is necessary to remove these
undeveloped silver and bromine ions

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and this is accomplished with sodium
file sulphate which dissolves the silver

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bromide leaving the metallic
silver atoms behind.

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But the positive silver making up the
visible image actually consists of clusters

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of these atoms distributed
throughout the gelatin layer.

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These particles are not
evident in an actual picture

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but may be seen under enormous
magnification as in this photo micrograph

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we have seen how the silver bromide
crystals receive install the latent image

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and learn that a developer
is needed to reveal it

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and of fixing back to make it permanent
in a Hollywood laboratory thousands of

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gallons of such developing
solutions are in daily use.

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They are compounded with the utmost care
using purified water untested chemicals.

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But what goes into a developer.

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First of all we need are using Agent which
hydro can own is typical There are a

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number of organic reducing agents
such as a lawn pyro liason Imanol

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and hard to come down.

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Which will convert the latent image to
metallic silver here we see some hydrophone

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added to water

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and a piece of exposed film
agitated in the solution

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but why doesn't it. Develop.

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Well the reason nothing happened is
because the developer worked only in the

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presence of an alkaline therefore we Next
add some sodium carbonate to the hard to

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pronounce solution.

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Now observe that development
takes place promptly.

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But also observe

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that the solution becomes discolored the
discoloration is due to the oxidation of

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the Heineken own

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and a solution like this would lose
strength very rapidly to prevent this rapid

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oxidation and loss of developing power.

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Sodium sulfite is included in the formula
to a solution of how to can only first

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add some sodium sulfite and then.

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The sodium carbonate.

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A piece of exposed film

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and immersed in the solution will
rapidly turn black indicating

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that the developing power is unimpaired
by the sodium sulfite But now we noticed

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that the solution remains perfectly
colorless our developing solution is now

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practically complete.

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It is desirable however to include a
small quantity of potassium bromide to

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restrain and reducing
action of the developer so

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that it will convert only the desired
I mentioned into metallic silver.

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Without affecting the surrounding
unexposed so bromide.

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The ability of potassium bromide to
retard the action of the developer is

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illustrated here in an exaggerated way

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but its class contain
complete developing solutions

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and excessive amount of potassium bromide
has been added to the one on the left.

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Now we see that the solution with the
excess throw mine does not develop at all.

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These then are the ingredients of a developing
a the developing or reducing agent.

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Say the preservative see the alkali

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or activator the restrainer in addition
to a developer we need affecting bad

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containing sodium five sulphate to
remove the undeveloped silver bromide by

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converting it to soluble Silver Fire
sulphate the primary function of the faking

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bath therefore is to remove the unexposed
undeveloped silver brown line this action.

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Not only makes the film
transparent where there is no M.

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and It also makes the image permanent.

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Since the action of light by itself will
gradually cause the UN removed silver

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bromide to darken in this
demonstration we observe

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that a piece of undeveloped film
becomes transparent. When agitated.

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And a strong solution of hypo.

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Because the silver bromide is converted
to soluble so versatile sulphate.

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You want. We call that development was
carried out in an alkaline solution.

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It is therefore desirable to make
the fixing bath acid in reaction.

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So that development will stop promptly
when the film is immersed in it.